On the habits of the caringa (Formica gracilipes, Gray
This short note by H. N. Ridley describes the nest-building behaviour, combat tactics, and feeding habits of the caringa ant (Formica gracilipes, Gray) in the Straits Settlements.
Summary
Ridley provides what he claims is the first description of the caringa’s method of constructing leaf nests. The ants select leaves from trees infested with scale insects (their primary food source), draw leaf edges together using their hooked hind claws—sometimes forming chains of ants to bridge gaps—and then sew the leaves shut with silk produced by larvae carried to the work site. Ridley documents a repair of a damaged nest on a Diospyros discolor tree, noting the work was completed in under a quarter of an hour (pp. 345–346).
He also records observations on the ants’ remarkable courage in combat, describing a battle between caringas and a larger species of black ant on a fig tree, in which a single caringa that had lost a leg and its abdomen still repelled three opponents before retreating. The ants are noted to be cannibalistic, to feed on scale insect honey until nearly transparent, and to share this honey with nest-mates by regurgitation (pp. 346–347).